Retaining walls can help you sculpt and reshape steeply graded lots into flat, terraced, usable sites.
Join Gasper Landscape Architect Christina Reeves to learn more about the three types of retaining walls Gasper Landscape Design & Construction build.
Boulder Retaining Walls
Boulder retaining walls are gravity walls, which means they use their weight to hold back the pressure of the retained earth. The base of the wall does not require a concrete footer and is instead the stone itself. The boulders are stacked upon each other, with each layer leaning or stepping back slightly to help hold up the wall. Boulder walls are usually more ‘open,’ allowing a more natural look and pockets for plants and soil. These walls are the most cost-effective to construct.
Decorative Block Retaining Walls
Decorative block retaining walls are constructed with pre-cast concrete blocks and do not require a concrete footer. These walls typically have a compacted stone base, and the first block course buried. The block is glued together with a durable paver adhesive. This gives the wall some flexibility to withstand the freeze/thaw movement we experience during the winter here in Pennsylvania. We typically build decorative block retaining walls under 36” in height, but some styles of decorative blocks can be used to construct higher walls if geogrid fabrics are used or when engineered to do so.
Masonry Retaining Walls
A masonry retaining wall is built on a full concrete footer at least 3 feet deep (the frost depth in our Philadelphia region). This ensures that no movement in the wall could cause cracking of the mortar joints. The wall is then built with concrete blocks and faced with a stone veneer. The veneer can be a real stone, a pre-cast concrete stone, brick, or stucco. It is important to cap a masonry wall to keep water out of the joints. Gasper typically caps its wall with Pennsylvania bluestone tread stock material. Masonry walls are the most expensive construction technique we offer because of the additional cost of the footer as well as the cost of the veneer stone.
Gasper’s naturally stacked stone walls are also constructed on a full footer so that the wall cannot move or fail. These walls may or may not have a concrete block core, depending on the desired finished appearance.
Note: Building codes require retaining walls over 30” in height to have some safety railing or barrier to prevent people from falling. Retaining walls over 48” in height will need to be reviewed by a structural engineer.
